If you've recently stopped smoking, then you ought to start eating more tomatoes and other fruits. According to a new study from Johns Hopkins University, doing so could help slow the decline of your lung function, by reversing some of the damage caused by smoking.

The researchers started by assessing the diet and lung function of over 650 adults in 2002, and then checked back on them 10 year later. Located in Germany, Norway and the UK, the people completed questionnaires regarding their diets and overall nutritional intake, plus they underwent a procedure that measured the capacity of their lungs to take in oxygen.

Factors such as age, height, sex, body mass index, socio-economic status, physical activity and total energy intake were all accounted for.

According to the university, it was found that ex-smokers who on average ate more than two tomatoes or more than three portions of fresh fruit per day experienced a slower decline in lung function than those who ate less than one tomato or less than one portion of fruit per day.

It should be noted that the effect was observed only with fresh fruits and tomatoes, and not with foods such as tomato sauce in which they're an ingredient. Also, as far as fruits other than tomatoes go, apples were found to be particularly beneficial.

"This study shows that diet might help repair lung damage in people who have stopped smoking. It also suggests that a diet rich in fruits can slow down the lung's natural aging process even if you have never smoked," says Vanessa Garcia-Larsen, the study's lead author. "The findings support the need for dietary recommendations, especially for people at risk of developing respiratory diseases such as COPD [chronic obstructive pulmonary disease]."

A paper on the research was recently published in the European Respiratory Journal.